The present invention relates to a method for simultaneously transmitting a plurality of independent commands over a transmission line. The commands are supplied to a coding facility at the sending end of the transmission line, and are there converted into transmittable code signals. At the receiving end of the transmission line, the transmitted signals are decoded and converted back into command signals which are supplied in parallel to a plurality of output terminals.
In the traditional systems, simultaneously occuring commands have been transmitted over a plurality of lines, allocated one line per command. At times during which no commands occur, the lines are not loaded or are only partially loaded.
It is also been possible to transmit simultaneously occuring commands with frequency-multiplex technology, using a broad frequency band which is divided into narrow sub-bands, with commands being allocated individually to the sub-bands. Frequency-division multiplex technology, however, requires modulation with different carrier frequencies and also requires transmission lines with sufficiently broad band characteristics to handle all of the sub-bands.
Simultaneously occuring commands can also be transmitted using time-division multiplex technology. In this technology, pulse frames of a constant length are formed and divided into successive time slots for each channel. When a great number of commands is expected, a correspondingly great number of channel slots must be provided so that the average delay time greatly increases, meaning the time between the appearance of a command at the sending station and the reception thereof at the receiving end of the transmission line.